1. Field of the Invention
The present invention relates in general to tract measuring devices and, in particular, to a surgical tool adapted to create and to measure the length of an incised tract.
2. Description of the Related Art
Over the years, devices have developed to allow fluid communication between an interior body cavity and an external surface of the body. Specifically, enteral feeding tubes and gastrostomy devices have been developed to provide nourishment to patients unable to otherwise ingest food due to the effects of a stroke, coma, serious injury or other medical problem.
Enteral feeding tubes are generally used only for limited periods of time while gastrostomy devices and, preferably low-profile gastrostomy devices, are used in long-term or permanent installations. A primary consideration during installation of either the feeding tube or the gastrostomy device is the relatively precise installed fit necessary to prevent infection, the migration of bodily fluids from the internal body cavity, and the proper formation of a mature stoma.
Since the length of the tract from the external surface to the inner body cavity varies from patient to patient due to various factors such as age, weight, and sex, the enteral feeding tube, which is typically adjustable to accommodate a range of incised tract lengths, is conventionally initially installed within the incised tract regardless of the anticipated period of need for fluid communication between the inner body cavity and the external surface. Thereafter, if long-term fluid communication is required, the feeding tube is removed and replaced by a gastrostomy device. The gastrostomy device is typically not adjustable to accommodate multiple tract lengths and therefore must be custom-fit to closely match the incised tract length for each patient.
Preliminary to the installation of any device to extend between the external surface of the body and the interior body cavity, an incised tract must be formed. The incised tract is conventionally formed by inserting a trocar and cannula through the external body surface and into the internal body cavity. Thereafter, the enteral feeding tube is installed within the just-formed tract.
Such an enteral feeding tube, as represented by U.S. Pat. No. 4,758,219, is typically introduced into the stomach via the mouth and esophagus, and then partially removed from the incised tract formed by a previously-inserted trocar and cannula. An internal end of the feeding tube mountingly accommodates an enlarged portion serving as a stop means while an external end of the feeding tube includes an adjustable skin protecting ring or bolster. The distance between the stop means and the bolster is adjusted by moving the bolster along the length of the feeding tube, firmly trapping the external surface of the body and the inner wall of the internal body cavity between the ring and stop means.
Other enteral feeding tubes are designed to be inserted through the incised tract from the external body surface into the internal body cavity, and include an internal end portion which is inflatable or otherwise expandable to define a stop surface. U.S. Pat. No. 5,074,846 is exemplary of devices of this type. A lengthwise adjustable outer skin engaging ring or bolster is used to compensate for variations in tract length, as in the '219 patent.
Outwardly deformable tubes or sheaths similar to the type shown in the '846 patent have also been used in catheters to retain the inner end of the catheter within an inner body cavity such as the bladder or peritoneum, as evidenced by U.S. Pat. Nos. 2,649,092 and 3,241,554. The catheter of the '554 patent also includes a depth gauge to indicate how far the catheter has been inserted into the abdominal wall.
Although the devices and methods for installing enteral feeding tubes illustrated above are satisfactory for short-term use, such feeding tubes are generally considered undesirable for long-term or permanent use due to the external length of the tube and awkwardness associated therewith. Therefore, for long-term installations, a low-profile gastrostomy device preferably replaces the enteral feeding tube after a mature stoma between the exterior body surface and internal body cavity has been established. The gastrostomy device, which, due to its low-profile nature, does not include a length adjustment feature, must be specifically sized to match the stoma length.
Therefore, prior to installation of a gastrostomy device, the stoma length is conventionally determined by measuring the length of the feeding tube from the external surface of the body to the internal stop surface. Typically, this is accomplished by placing a reference mark on the feeding tube adjacent the external surface, removing the feeding tube from the body by reversing the installation steps, and then measuring the distance from the reference mark to the stop surface. The appropriate size of the gastrostomy device is derived from this measurement. Thereafter, the gastrostomy device is inserted into the stoma to complete the replacement procedure.
Alternatively, stoma length can be determined by a measuring device such as disclosed by U.S. Pat. No. 4,972,845. The stoma measuring device of the '845 patent includes an elongated tubular member which provides scale indicia on an exterior surface thereof. A distal end of the tubular member is inflatable to serve as a stop means to temporarily prevent the removal of the distal end from an inner body cavity, allowing the length of the stoma to be measured via the scale indicia.
U.S. Pat. No. 4,863,438, which is assigned to the assignee of the present invention and expressly incorporated herein by reference, is exemplary of low profile gastrostomy device which is designed to replace an enteral feeding tube within an existing stoma. A stylet is used to elongate and stretch the enlarged intragastric head of the gastrostomy device, which is thereafter pushed through the stoma into the internal body cavity. A tubular midportion is received by the stoma while a pair of oppositely directed wings engage the external body surface. Additional gastrostomy feeding ports are shown in U.S. Pat. Nos. 4,850,953 and 4,944,732.
In all of the aforementioned gastrostomy devices, the gastrostomy device must fit snugly within the stoma between the inner wall of the internal body cavity and the external body surface. In the aforementioned prior art this has necessitated the initial installation of an enteral feeding tube in the incised tract to allow the incised tract to mature and become a permanent stoma and to thereafter allow an accurate measurement of the stoma length.
Therefore, in the aforementioned prior art, the steps of forming an incised tract, inserting an enteral feeding tube, allowing the incised tract to mature into a stoma, removing the enteral feeding tube, and measuring the stoma length are required before the gastrostomy device can be installed within the stoma.
In response to this costly and time consuming process, it has been proposed that a low-profile gastrostomy device be directly installed within an incised tract without the need for the preliminary placement of a feeding tube therein. Initially placing a low-profile gastrostomy device in an incised tract allows the patient to immediately benefit from the advantages inherent in use of a low profile gastrostomy device as opposed to an enteral feeding tube. Moreover, eliminating the need for the initial placement of a feeding tube reduces the cost and trauma traditionally associated with the installation of a gastrostomy device. U.S. Pat. No. 5,084,014, which is owned by the assignee of the present invention and expressly incorporated herein by reference, is directed towards a low-profile gastrostomy device adapted to be mounted within a recently-formed incised tract.
The '014 patent discloses a package for the initial placement of a gastrostomy device wherein an external body surface-engaging portion is outwardly pulled through the incised tract. The package includes a shroud which retains wing-like members of the external body surface-engaging portion in a deformed configuration, generally parallel to a tubular midportion of the device. Installation occurs by inserting the package into the stomach, pulling it through the incised tract until an enlarged intragastric portion engages the inner wall of the stomach, and thereafter removing the shroud to allow the wings to return to their undeformed, outwardly extending configuration. Once installed, the device functions generally identically to the gastrostomy device disclosed in the '438 patent.
Although the installation package of the '014 patent works satisfactorily, proper sizing of the gastrostomy device still requires the prior measurement of the incised tract length.
United States patent application Ser. No. 07/767,124, which was filed on Sep. 27, 1991, entitled "TRACT MEASURING DEVICE", the disclosure of which is expressly incorporated herein by reference, is directed towards a device and method for measuring the length of an incised tract. The device includes an elongated member having scale indicia along at least a portion of its length, and stop means at one end of the scale indicia.
In the disclosed method of the '124 application, an incised tract between an external surface of a body and an inner wall of an internal body cavity is formed by a trocar and cannula. Thereafter, the device is inserted into the stomach via the mouth and esophagus, and a distal end of the elongated member is inserted through the incised tract until the stop means engages the inner wall of the internal body cavity. The elongated member extends out of the incised tract, making the scale indicia thereon visible and allowing the determination of tract length. Thereafter, the incised tract measuring device is removed and a low profile device sized to match the measured tract length is installed, preferably in accordance with the device and method of U.S. Pat. No. 5,084,014.
Although the aforementioned incised tract measuring device and method represents an improvement over the prior art method of measuring length, it suffers from the disadvantage that it requires insertion and removal via the esophagus, creating additional irritation and trauma for the patient. Moreover, a separate trocar and cannula are required to form the incised tract prior to insertion of the measuring device through the tract.
Therefore, there exists a need in the art for a surgical tool for the measurement of an incised tract length which does not require insertion or removal via the esophagus. Moreover, there exists a need in the art for a surgical tool which is capable of creating and measuring an incised tract.